diff --git a/include/SFML/Audio/Sound.hpp b/include/SFML/Audio/Sound.hpp
index f68852e87..3d53fe6c4 100644
--- a/include/SFML/Audio/Sound.hpp
+++ b/include/SFML/Audio/Sound.hpp
@@ -58,7 +58,7 @@ public :
     /// \param buffer Sound buffer containing the audio data to play with the sound
     ///
     ////////////////////////////////////////////////////////////
-    Sound(const SoundBuffer& buffer);
+    explicit Sound(const SoundBuffer& buffer);
 
     ////////////////////////////////////////////////////////////
     /// \brief Copy constructor
diff --git a/include/SFML/Graphics/VertexArray.hpp b/include/SFML/Graphics/VertexArray.hpp
index c52b6c205..1c2ebee42 100644
--- a/include/SFML/Graphics/VertexArray.hpp
+++ b/include/SFML/Graphics/VertexArray.hpp
@@ -61,7 +61,7 @@ public :
     /// \param vertexCount Initial number of vertices in the array
     ///
     ////////////////////////////////////////////////////////////
-    VertexArray(PrimitiveType type, unsigned int vertexCount = 0);
+    explicit VertexArray(PrimitiveType type, unsigned int vertexCount = 0);
 
     ////////////////////////////////////////////////////////////
     /// \brief Return the vertex count
diff --git a/include/SFML/Network/Ftp.hpp b/include/SFML/Network/Ftp.hpp
index a5ab108a0..55d09599d 100644
--- a/include/SFML/Network/Ftp.hpp
+++ b/include/SFML/Network/Ftp.hpp
@@ -143,7 +143,7 @@ public :
         /// \param message Response message
         ///
         ////////////////////////////////////////////////////////////
-        Response(Status code = InvalidResponse, const std::string& message = "");
+        explicit Response(Status code = InvalidResponse, const std::string& message = "");
 
         ////////////////////////////////////////////////////////////
         /// \brief Check if the status code means a success
diff --git a/include/SFML/System/Lock.hpp b/include/SFML/System/Lock.hpp
index e6996776e..c5667db9e 100644
--- a/include/SFML/System/Lock.hpp
+++ b/include/SFML/System/Lock.hpp
@@ -52,7 +52,7 @@ public :
     /// \param mutex Mutex to lock
     ///
     ////////////////////////////////////////////////////////////
-    Lock(Mutex& mutex);
+    explicit Lock(Mutex& mutex);
 
     ////////////////////////////////////////////////////////////
     /// \brief Destructor